A major problem in all pulse technique systems, in particular in data processing systems, is the ongoing problem of checking whether or not the system is operating correctly. In purely digital systems, it is a common practice to create, or makeup, small problems which use different segments of the system's circuitry or hardware. These small problems are inserted as steps in lengthy programs. In short, the lengthy programs are interrupted and the short problems are "run." The solutions to the short problems are checked automatically against predetermined answers stored in memory, and if the solutions "check out", the user (or the system) assumes that the system is functioning correctly. In accordance with some other techniques, a problem being run is computed twice, independently and simultaneously, and compared. If a good match is found, the system is assumed to be operating correctly. If, in either of the foregoing techniques, the comparison indicates an error, the system is assumed to be operating incorrectly. It is a common practice in employing such techniques, to program the system to try more than one time if an error is generated.
It is not as simple to verify analog data as it is to verify digital data. However the present system does provide a means, employing already available components, to readily verify that a system, which is handling both digital and analog data signals, is in fact handling such signals correctly, and is in fact handling the transformations thereof correctly.